Let me start with: whoever it was that told me this was on sale that day on Amazon, I thank you wholeheartedly. I only bought it on a whim, not knowing anything about it except that a bunch of Internet people said it was good. It blew my non-existant expectations out of the water. Along with TWEWY and another game I can't really decide on yet, this is in my opinion one of the top 3 DS games.
Everything about this game is so great, especially the "Oh, wait, WHAT? What the heck?" kinda moments, and the puzzles were the right balance between "satisfying to solve, but simple/short enough that in additional playthroughs it wasn't a pain in the ass to do them again", and the music did a great job of highlighting the mood of each situation (especially a certain track named "Quietus".) The story was also good enough to keep me playing into stupid hours of the morning (now that usually happens with games, but this game kept me up even longer.)
Also, THOSE ENDINGS. It's been a long time since I've been that motivated to see all of a game's endings. The way this game handles the "multiple endings" mechanic was crazy. I don't think I've seen anything like that anywhere else.
If you wanted to know what order I got the endings in:
Axe -> Submarine -> Knife -> Coffin -> Safe -> True
And I wouldn't have had it any other way. It's pretty funny that the only reason I got the Axe one the first time was because I didn't say [Ice-9] to Seven, though. I was on the right track..
Usually with the final parts of games, I can get behind the "hell yeah, let's do this!" attitude that protagonists give off, but I don't think I've ever been so emotionally involved with what the character was actually doing for some of the parts, especially like I was with that last puzzle.
After finishing this game, I lay where I had been playing it for what must have been hours trying to piece everything together, mostly the stuff the game doesn't come right out and tell you to your face. Which is great. I even wrote down a bunch of questions I wasn't sure of the answers to so I wouldn't forget, because I wanted to know so bad (that link to those answers in that other thread did a good job at tying up most of that, though.)
..If you didn't notice by now, I really liked this game. Going back to that trailer that came out 2 weeks ago for the sequel has gotten me crazy excited for something else like this.
There's a lot more I want to say, but I can't seem to find the right words and heck, hardly anyone is going to read this far anyways.
tl;dr? This game's great. If you have a DS and you haven't played this already, get it. Crazy praising of videogame over.